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Attitude sensor and actuator interfacing for micro-satellitesDlamini, Zamokwakhe P. (Zamokwakhe Peacemaker) 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The purpose of this thesis was to design and test the interfaces of sensors and actuators. In the
complete Attitude Determination and Control System CADCS) the Interface Control Processor
(ICP) must be interfaced to various sensors and torquers.
The testing of interfaces involves the simulation of sensors and actuators and also two of the
Attitude Control Processor's functions, i.e. sending actuator commands and receiving sensor
data. The tested interfaces are for two actuators and three sensors. Both analog and digital
sensors and actuators are interfaced i.e. reaction wheels, magnetorquers, magnetometer and
horizon /fine sun sensor. The simulated sensors and actuators are to be employed on three axis
controlled, low earth o~biting micro-satellites.
To test the interfaces, a test circuit was developed and the design is presented. Finally the
software to facilitate the testing was developed and is also presented with the analysis based on
protocol implementation and data rates. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis was om sensor en aktueerder koppelvlakke te ontwerp en te toets. In
die volledige Attitude Determination and Control System CADCS) moet die Interface Control
Processor CICP) aan verskeie sensore en torquers gekoppel word.
Die toets van koppelvlakke behels die simulasie van sensore en aktueerders en ook twee van die
Attitude Control Processor (ACP) se funksies, naamlik die stuur van aktueerder bevele en die
ontvang van sensor data. Die koppelvlakke vir twee aktueerders en drie sen sore is getoets.
Beide analoog en digitale sensore en aktueerders is gekoppel, naamlik die reaksiewiele,
magneetspoele, magnetometer en horison I fyn son sensor. Die gesimuleerde sensore en
aktueerders sal gebruik word op drie-as beheerde, lae aardbaan mikrosatelliete.
Om die koppelvlakke te toets is 'n stroombaan ontwikkel waarvan die ontwerp hier aangebied
word. Sagteware om die toetse te fasiliteer is ontwikkel en word ook hier aangebied tesame met .
analises gebaseer op protokol implementering en data tempo's.
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A satellite signal recognition systemOiesen, Eric A. 05 September 2009 (has links)
Geosynchronous communications satellites provide a wide variety of services. They carry wideband signals, such as television, and narrowband signals, such as business data networks. This paper describes a signal recognition system for the narrowband signals found on Ku-band satellites. Using readily available equipment, it saves observed signals which are later processed into an observation report. Observed signals are labeled using a decision tree, which is a pattern recognition technique. Each observation report also includes center frequency, bandwidth, and carrier-to-noise ratio. This paper presents the design and implementation of the signal recognition system. Results from the system are included. / Master of Science
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Attitude determination and control system of a nanosatelliteSchoonwinkel, Johannes 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2007. / The aim of this project was to design and test a partial attitude determination
and control system for a nanosatellite. The reaction wheel system was
designed and tested as an actuator for the nanosatellite. This reaction wheel
system consists of four reaction wheels mounted in a tetrahedral formation.
A rate sensor system was also designed and its viability for this space application
was examined. The rate sensor system consists of 3 orthogonally
mounted planes, each with three rate sensors mounted on it. Hardware-inthe-
loop tests were used along with an air bearing experimentational setup,
which created near frictionless circumstances, to prove the effectiveness of
the designed reaction wheel setup. The results following from this project
were the following: The reaction wheel system proved to be an adequate actuator
for this nanosatellite application and the rate sensor systemwhich was
analysed proved to be inadequate for a nanosatellite application.
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An investigation of satellite maneuvering and orientation strategies using an air bearing tableKuhn, Eckhardt 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / In this thesis, the maneuvering and orientation of an inspection/service satellite is investigated.
This thesis will demonstrate a simplified satellite maneuver around another
satellite (for docking purposes). This is illustrated with a cart on an air bearing table
(frictionless environment) which simplifies the problem to two dimensions.
A mathematical model of the system was designed and simulated (Matlab) for this maneuver.
With the simulation, different strategies were considered to maneuver the cart
in a circle around another object. The conclusion was made that approximating the circle
with segments would conserve propellant. This strategy was implemented on the air
bearing table.
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Design of an aerodynamic attitude control system for a CubeSatAuret, Jacoba 03 1900 (has links)
Thesis (MscEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The Cape Peninsula University of Technology, in collaboration with Stellenbosch University,
is developing a 3-unit CubeSat for a low earth polar orbit. The two main payloads
are a camera and a radio frequency beacon. This beacon will be used to calibrate the
radar antenna patterns of an antenna of the Hermanus Magnetic Observatory at their
base in Antarctica. This thesis describes the development of an aerodynamic attitude determination
and control system needed to achieve three-axis stabilisation of the satellite
and to perform accurate pointing of the camera.
The satellite structure is designed to utilise aerodynamic means of control. It includes
four feather antennae for passive pitch-yaw stabilisation and two active aerodynamic roll
control paddles. The sensors used are a three-axis magnetometer, ne sun sensor and
nadir sensor. Three attitude determination methods are investigated, namely the Triad,
Rate Kalman Filter and Extended Kalman Filter algorithm. Apart from the aerodynamic
control elements of the satellite, three magnetic torque rods and three nano-reaction
wheels are also included in the design. Three control modes for the satellite are identi ed
and various control methods are investigated for these control modes.
The various attitude determination and control methods are evaluated through simulations
and the results are compared to determine the nal methods to be used by the
satellite. The magnetic Rate Kalman Filter is chosen as attitude determination method
to be used when the satellite is tumbling and a combination of the sun Rate Kalman
Filter and the Triad algorithm is to be used when the satellite experiences low angular
rates. The B-dot and Y-spin controller is chosen for the detumbling control mode, the
aerodynamic and cross-product control method for the three-axis stabilisation control
mode and the quaternion feedback control method for the pointing control mode of the
satellite. The combination of magnetic and aerodynamic control proved to be su cient
for the initial stabilisation of the satellite, but the three nano-reaction wheels are required
for the pointing control of the imaging process. / AFRIKAANSE OPSOMMING: Die Kaapse Skiereiland Universiteit van Tegnologie, in samewerking met die Universiteit
van Stellenbosch, is tans besig met die ontwikkeling van 'n 3-eenheid CubeSat vir 'n
pol^ere, lae aard-wentelbaan. Die twee loonvragte van die satelliet bestaan uit 'n kamera
en 'n radiofrekwensie-baken. Die radiofrekwensie-baken sal gebruik word om 'n antenna
van die Hermanus Magnetiese Observatorium, by hul basis in Antarktika, se radar antenna
patrone te kalibreer. Hierdie tesis beskryf die ontwikkeling van 'n aerodinamiese
ori entasiebepaling en -beheerstelsel wat benodig word om die satelliet in drie asse te
stabiliseer en om die kamera noukeurig te rig.
Die satelliet se struktuur word ontwerp vir aerodinamiese beheer. Dit sluit vier veerantennas
in vir passiewe duik-gier beheer, asook twee aerodynamiese rolbeheer
appies
vir aktiewe beheer. Die sensors wat gebruik word sluit 'n drie-as magnetometer, fyn
sonsensor en nadirsensor in. Drie ori entasiebepalingsmetodes word ondersoek, naamlik
die Drietal, Tempo Kalman lter en die Uitgebreide Kalman lter algoritmes. Buiten die
aerodinamiese beheerelemente van die satelliet, word daar ook drie magneetstange en
drie nano-reaksiewiele ingesluit in die ontwerp. Daar word onderskeid getref tussen drie
beheermodusse en verskeie beheermetodes word ondersoek vir hierdie beheermodusse.
Die verskeie ori entasiebepalings- en ori entasiebeheermetodes word ge evalueer deur middel
van simulasies en die resultate word vergelyk om die beste metodes vir die satelliet se
gebruik te bepaal. Die magnetiese Tempo Kalman lter word gekies as ori entasiebepalingsmetode
vir 'n tuimelende satelliet en die kombinasie van die son Tempo Kalman lter en
Drietal algoritme word gebruik vir 'n satelliet met lae hoektempos. Die B-dot en Y-spin
beheerder word gekies vir die tuimelbeheermodus, die aerodinamiese en kruisproduk beheermetode
vir die drie-as-stabilisasie-beheermodus en die kwaternioon terugvoer beheermetode
vir die rigbeheermodus van die satelliet. Daar word bepaal dat die samespanning
van magnetiese en aerodinamiese beheer voldoende is vir die aanvanklike stabilisering
van die satelliet, maar dat die drie nano-reaksiewiele benodig word om die kamera te rig
tydens die beeldvormingproses.
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Control moment gyro actuator for small satellite applicationsBerner, Reimer 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / The aim of the thesis is to design a Control Moment Gyro (CMG) actuator which can be
used in small satellite applications. The hardware and software of the CMG has to be
designed according to specifications given. A satellite fitted with these CMGs has to be
able to do a 30 degree rotation within 10 seconds.
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Reusable software defined radio platform for micro-satellitesVan Wyk, John Foster 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / This thesis describes the design and implementation of a software platform for software
defined radio (SDR). This platform was to form part of an experimental satellite payload.
Several other experiments were also housed on this platfrom and subsequently had to be
incorporated into the design. The hardware components of the payload were already de-
termined at the start of the project but firmware had to be created as part of the project.
The software platform was based on the Linux kernel. Device drivers had to be designed for
the hardware and firmware components. These drivers were designed so that standard Unix
utilities could be used to interact with them. This allowed for easy testing of the system
and the programs running on it. The use of the platform for modulation and demodulation
of analogue signals was demonstrated using a proof-of-concept SDR application.
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Strategies for the control of a satellite with thruster misalignmentVan Daalen, Corne E. 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / This project investigates two problems related to satellites that contain cold gas thrusters and reaction wheels. The first problem concerns the estimation of the thruster force response to a pulse command. An optimal data integration method is developed and implemented to estimate the thruster force output from a number of noisy sensors. The second problem occurs when the output force vector of a thruster mounted on a satellite is misaligned with the centre of mass with the satellite. As a result a disturbance torque is generated on the satellite during thruster operation.
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Volumetric data throughput optimisation by dynamic FEC bearing frame length adaptationChristelis, Christian 03 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The telecommunications link between a LEO satellite and a rural ground station
with a non-tracking antenna, has a strongly varying link quality and
a short communications window. The satellite acts as a store-and-forward
node between ground stations. The TC-SDLP and an FTP protocol form a
shallow protocol stack, which excludes unneeded protocol functionality and
the resulting overhead. Coding gain, introduced by BCH FEC in the TCSDLP,
allows for link quality improvement.
The core of this thesis is an improvement of the TC-SDLP to maximise effective
payload data throughput, or goodput. This improvement was achieved
by creating an optimal segment length selection metric based on the BER.
Since the BER is not determinable from within the TC-SDLP, the metric was
twice determined; once based on the FER and finally based on time delays.
The work includes an extensive background study, which consists of space
standardisation, orbital physics, error detection and correction, space datalink
protocols, data throughput and culminating in the protocol stack design.
The project specific link budget calculation is presented. The optimal
segment length policy was mathematically determined.
Asimulation model of the TC-SDLP was used as a proof of concept for the
effective throughput and give a performance benchmark. Finally a TC-SDLP
implementation offers a real world performance demonstration. / AFRIKAANSE OPSOMMING: Die telekommunikasie skakel tussen ’n lae aardomwenteling (LEO) sateliet
en ’n plattelandse grondstasie met ’n nie-volg antenna, het ’n skakelkwaliteit
wat in ’n groot mate varieer en ’n kort kommunikasievenster. Die sateliet tree
op as ’n stoor- en- aanstuur node tussen grondstasies. Die TC-SDLP en ’n leêr
oordrag protokol (FTP) vorm ’n vlak protokol stapel, wat onnodige protokol
funksionaliteit en die gevolglike opkoste uitsluit. Kode aanwins, wat deur
die BCH FEC in die TC-SDLP, aangebring word, verbeter die skakelkwaliteit.
Die kern van hierdie tesis is ’n verbetering van die TC-SDLP om sodoende
die ware deurvoer van nuttige vragdata te maksimimeer. Hierdie verbetering
is bereik deur die skep van ’n optimale segmentlengte-seleksie metode
gebaseer of die bit fout tempo (BER).
Aangesien die BER nie bepaal kan word vanuit die TC-SDLP nie, is die
maatstaf twee keer bepaal; die eerste keer is die bepaling gebaseer op die
raamwerk fout tempo (FER) en die finale bepaling op tyd vertragings.
Die tesis sluit ’n omvattende agtergrondstudie in, wat bestaan uit ruimte
standardisering, wentelbaan fisika, die opspoor en regstel van foute, ruimte
inligtingskakel protokol en deurstuur van data wat uitloop op die protokol
ontwerp. Daar word aangedui hoe die berekening van die begroting vir die
skakel van toepassing op die spesifieke projek, gedoen is. ’n Wiskundige
analise van die optimale segmentlengte s ook gedoen.
’n Simulasie model van die TC-SDLP is gebruik as ’n bewys van die konsep
vir die ware deurset en gee ’n prestasie maatstaf. Laastens bied die TCSDLP
implementering ’n ware wereld prestasie demonstrasie.
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The design of a communication protocol for a distributed ADCS for SUNSAT 2Magano, Abram Tshwaro 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: One of the main subsystems of SUNSAT is the Attitude Determination and
Control System (ADCS), responsible for the orientation and positioning of the
satellite. Due to the integrated architecture of the system, several shortcomings
were identified. A possible solution to the problems is the implementation of a
distributed system. The design of a communication protocol for a distributed
system is the focus of this thesis.
An investigation on different network topologies and communication protocols as
well as error control techniques is carried out to establish a combination that
meets the requirements of the ADCS. Based on defined protocol specifications a
detailed protocol design is proposed. Then the protocol is implemented using a
layered software structure that emanates from the OSI layering model, to provide
well defined software structures and interfaces. A series of measurements have
shown that the protocol meets the functional requirements of the ADCS and
further provides reliable data transfer on the network. / AFRIKAANSE OPSOMMING: Een van die vernaamste dele van SUNSAT is die "Attitude Determination and
Control System" (ADCS) wat verantwoordelik is vir die orientasie en
posisionering van die satelliet. Verskeie tekortkomminge as gevolg van die
geYntegreerde argitektuurvan die stelsel, is geYdentifiseer. 'n Moontlike oplossing
vir die probleme is die implementering van 'n verspreide stelsel. Die ontwerp van
'n kommunikasie protokol vir 'n verspreide stelsel is die fokus van die tesis.
'n Ondersoek na verskeie netwerk topoloqie en kommukasie protokolle, asook
foutbeheer tegnieke is uitgevoer om vas te stel watter kombinasie die ADCS se
vereistes sal bevredig. 'n Gedetaileerde protokol ontwerp is voorgestel gebaseer
op gedefineerde protokol spesifikasies. Hierdie protokol is toe geYmplementeer
deur gebruik te maak van vlak gestruktureerde sagteware wat afkomstig is van
die OSI model, met die oog op goed gedefineerde sagteware strukture en
koppelvlakke. 'n Reeks meetings het aangedui dat die protokol die funksionele
vereistes van die ADCS bevredig en dat dit verder betroubare data verplasing
oor die netwerk verskaf.
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